This invention relates to a rack and pinion steering mechanism and the attachment thereof to an automotive vehicle, especially a passenger car, wherein the rack and pinion steering mechanism is elastically mounted to a part integral with the vehicle.
Rack and pinion steering mechanisms are known which are joined to a part fixedly attached to the vehicle by means of a direct threaded connection, as illustrated, for example, in DAS (German Published Application) 1,215,010. This rigid type of mounting has the result that the steering has a "jerky" effect, ensuing in an unharmonious, angular steering force characteristic.
In another, generally conventional type of mounting, the gearbox of the rack and pinion steering mechanism is surrounded clamplike by two brackets with the interposition of rubber strips, wherein the brackets are threaded together with the chassis. This rubber-elastic mounting of the gearbox extensively overcomes the disadvantages inherent in the aforementioned state of the art. However, the most important disadvantage of such rubber elastic mounting is that this type of mounting is not resistant to axially directed thrust forces whereby the gearbox of the rack and pinion steering can be shifted sideways in case of a thrust force effective in the axial direction, so that in certain cases the threaded connection is loosened.
It has also been proposed according to DOS (German Unexamined Laid-Open Application) 1,957,462 to elastically support the gearbox of the rack and pinion steering mechanism by means of two rubber rings inserted in the gearbox. This type of support, however, can disadvantageously absorb only axially directed thrust forces. Furthermore, this elastic bearing is very expensive from a constructional viewpoint. In the alternative type of arrangement of the reference in question, shown in FIG. 2, only an axially directed, elastic thrust absorption is possible, on the one hand, and furthermore, on the other hand, the bolt fixing the arrangement in place against axial shifting has the effect of a solid sound-conducting bridge.
This invention contemplates an arrangement which overcomes the problem of mounting the gearbox of a rack and pinion steering mechanism in a manner resistant to axial thrust on a part affixed to the vehicle (integral with the vehicle) by simple means, and thus to elastically absorb the forces effective on the gearbox in all directions.
To solve this problem, the invention contemplates providing a diagonally rigid holding means surrounding a gearbox of the rack and pinion steering mechanism in frictional engagement therewith by way of an elastic intermediate layer, wherein the holding means, in turn, is attached to a part integrally joined to the vehicle.
In a preferred embodiment of the invention, the provision is made to join the holding means on a broad base to the part integrally joined with the vehicle, by means of two screws wherein the elastic intermediate layer is arranged essentially in the zones near the end faces of the holding means.
A suitable preferred arrangement of the invention is distinguished in that the holding means for the gearbox consists of a carrier casing which is detachably connected with the front-axle support with its long side facing this support, wherein the shanks of the screws are disposed at a right angle to the longitudinal axis of the gearbox.
Further advantageous embodiments and features of the invention are characterized in the dependent claims.
Within the scope of the present invention, it is contemplated to provide that, in a rack and pinion steering mechanism according to the introduction which is equipped with a steering damper or shock absorber, the piston rod of this damper, joined to a holder -- the latter being in turn attached to a part executing the steering motion -- is to be protected against deleterious influences due to water and dirt. Furthermore, the steering damper is to be disposed so that a minimum bending moment is produced in its mounting elements.
In a preferred embodiment of the invention the steering damper is placed in close spatial relationship with the gearbox and the piston rod of the steering damper and the gear rack together are encompassed by a sealing bellows.
In a further development of this last-mentioned embodiment of the invention, the provision is made that the steering damper is arranged either in the immediate vicinity of the outer wall of the gearbox or it is combined with the gearbox into one unit.
The casing of this invention combines, with structurally simple means, an elastic support of the gearbox and the thrust-resistant mounting thereof at the front-axle support. By the encapsulation of the steering damper, optionally to be utilized, into the carrier casing, the damper is protected against deleterious entrance of water and dirt, as well as against mechanical damage. Furthermore, excessive stresses on the screws joining the carrier casing with the front-axle support are avoided. The advantage of certain preferred embodiments of the invention resides in that the rack and the piston rod are entirely surrounded by the sealing bellows providing complete tightness with regard to air and moisture.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.